Heavy duty window balance



Feb. 26, 1957 KENYQN 2,782,456

HEAVY DUTY WINDOW BALANCE Filed April 21, 1954 4 Sheets-Sheet l INVENTORBqfra'no F Kenyon ffor'neg Feb. 26, 1957 B. F. KENYON HEAVY DUTY WINDOWBALANCE 4 Sheets-Sheet 2 Filed April 21, 1954 IN V EN TOR. Bfrfrono FKenyon Affomey Feb. 26, 1957 B. F. KENYON HEAVY DUTY WINDOW BALANCE 4Sheets-Sheet 3 Filed April 21. 1954 INVENTOR.

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HEAVY DUTY WINDOW BALANCE Filed April 21; 1954 4 SheetsSheet 4 JBerfrand jail/on y. W 5. W

ffomev limited than it now is.-

United States Patent HEAVY DUTY WINDOW BALANCE Bertrand F. Kenyon, GrandRapids, Mich., assignor to Mechano Gear Shift Company, Grand Rapids,Mich, a corporation of Michigan Application April 21, 1954, SerialNo.424,559

3 Claims. (Cl. 16198)' Thisinvention relates to window orv likebalances, being generally concerned with balances ofthe wound springtype, which have spring actuated rotative drums and tapes or cableswound on the drums attached to a vertically sliding. window sash whichis raised and lowered.

The weight of a window to which such type of balance is applied isconstant. The spring power acting against such weight varies with thedrum rotation, the spring in general being wound and exerting a strongerlifting force; which progressively increases as the window sashislowered and likewise decreases when the sash is raised. Without thefactor of frictionof the window. sash sliding inthe frame in which it ismounted, and also inertia, the range oftravel of a window sash would beeven more As it is, the range of. vertical travel or movement of awindow sash is curtailed and limited. It frequently happens that onloweringa window sash the lifting force of the spring balance isincreased to.- such: an extent that the sash may be lifted above adesired lowermost position, particularly ona decrease of friction as mayoccur, at least with wood windows. and frames, with changingatmospheric; conditions. Likewise, as the spring lifting force decreasesas a sash is raised; apoint is, quickly reached where the balance willnot; hold a windowsash in its upper. position ifit is liftedabove suchpoint. Accordingly, thenormal spring balance of the wound spring typehas heretofore been limited in use. to window sashes, the lifting andlowering of whichis small compared to many sashes, particularly inwindows of the so-called heavy duty charactenusually of metal, slidably'mounted, for vertical movements in metal frames.

Window sashes which are large and have a relatively long vertical travelhave not been successfully equipped withspring balancesbecause ofsuchwidely varying and changing forces of springs in spring balancesapplied to the sliding window sash, the weight of which is constant.

In the present invention it is an object and purpose thereof to balancea window sash or the like of whatever weight, light, medium or heavy, bya wound spring balance in a manner to obtain substantially the sameresults asv those obtained by weightswhich have long been used tosubstantially counter-balance the weight of the window sash. and withwhich. any range of vertical travel ofa window sash may be effectively:taken careof.

To this end, the weight of a window sash being constant, the moment offorce acting upon the sash throughout its travel is renderedsubstantiallyv constant at all points of its travel, at leastapproximately so, so as to be practical and serviceable and serve itsdesired functions with any and all weights of window sashes and with anyand all lengths of travel thereof. As the spring (or springs) is woundand spring force increased progressively, the moment arm through whichthe force operates is correspondingly progressively decreased. As aspring unwinds, as when a window sash is moved upwardly, the initialmoment arm being at its minimum progressively increases so that thechanging spring force, at all points in the vertical travel of theWindow sash, either up or down, multiplied by the changing lengths ofthe moment arm remains substantially or approximately constant, and hasat all times the same approximate ratio thereof to the weight of thewindow sash to which the balance is applied.

An understanding of the invention and of the embodiments which have beenmade and which have proven best for windows of heavy weight, those ofintermediate Weight, and those of light weight, may be had from thefollowing description, taken in connection with the accompanyingdrawing, in which,

Fig. l is a more or less diagrammatic view showing the use of one of thespring balances of my invention applied to a heavy weight window sashmounted for vertical movement in a window frame.

Fig. 2 is a like view showing two of such balances connected with thewindow sash.

Fig. 3 is an elevation of the interior structure of the sash balanceused in Fig. l, with a side of the housing removed therefrom.

Fig. 4 is an elevation of a spring winding means used to give an initialpreselected tension force to the spring.

Fig. 5 is a longitudinal vertical section, substantially on the plane ofline 5-5 of Fig. 6 looking in the direction indicated.

Fig. 6 is a horizontal section, substantially on the plane of line (--6of Fig. 5, said section being taken substantially inthe plane of theaxes of the spring carrying drums.

Fig. 7v is a partial vertical section and elevation of a spring bandbalance of the type for use with light weight window sashes, the planeof the section being substantially on line 77 of Fig. 9.

Fig. 8 is a central vertical transverse section substantially on theplane of line 8-3 of Fig. 7.

Fig. 9. is a horizontal section and plan view, substantially on theplane of line 99 of Fig. 7.

Fig. 10 is a horizontal section, substantially on the plane of line 1010of Fig. 11 of an embodiment of the invention which maybe used withwindowsashes of intermediate weights.

Fig. ll is a partial vertical section and elevation, the plane of thesection being substantially on the plane of line 1111 of Fig. 10, and

Fig. 12 is a partial section and elevation of separated elements usedfor providing the spring carrying drums in the structure shown in Figs.10 and 11.

Like reference characters refer to like parts in the different figuresof the drawings.

The balance shown in- Figs. 5 and 6 is a balance for heavy duty, used inembodying my invention in serving heavy weight window sashes whichusually are of metal, vertically slidable in metal frames. In structure,a housingis provided having a narrow elongated base 1 with spacedparallel vertical sides 2 extending upwardly from opposite longitudinaledges of the base, and with a covering member S closing the housing atthe ends and top, The. housing made of sheet metal may be made innumerous waysof sheet metal parts whichwill be secure.- ly connectedtogether when the balance is assembled.

Between the opposite sides 2 of the housing, two spaced horizontalshafts or arbors 4 and 5 are mounted and permanently secured at theirends. The shaft 5 has atclrum thereon consisting of'a central hub 6(Fig. 6) located. around the shaft 5, a circular web 7 and a flange 8which has two drum surfaces, the one of larger diameter' at 811 and ofsmaller diameter at 9, the cross sectional form of the drum. flangebeing fully shown in Fig. 6. Around the larger diameter portion 8a, acon- M secutive series of gear teeth'10 are provided integral with thedrum and cut in a projecting rim at the inner open side of the drum.

The open side of the drum is closed by a closure member having a centralhub 11 which telescopes over the hub 6, a web 12 parallel to the web 7of the drum, which web has the same diameter as the diameter of theenlarged section 8a of said drum, and at the peripheral edges of which,a second continuous series of gear teeth 13 are made, the pitch diameterand the exterior diameter of the teeth and 13 being the same.

Within the drum a windable spring 14 of spring band material is mounted,its inner end being securely connected with the hub 11 and its outer endwith the flange 8 of the drum described. It will be noted that the outersides of the webs 7 and 12 are substantially close to the inner sides ofthe opposed sides 2 of the housing.

A second drum is mounted for turning about the axis of the shaft orarbor 4 (Fig. 6). It has a central hub 15 similar to the hub 6, a web 16similar to web 7, and at the outer edges of the web 16, a flange havinga relatively heavy body 17, and a smaller diameter cylindrical section18 extending therefrom.

A closure for the open side of the last described drum includes acentral hub 20 around the hub 15, and a web 21 similar to web 12. Gearteeth 22 meshing with the teeth 13 of the first described drum closureand of the same pitch diameter as the teeth 10 are formed around theperiphery of such closure, a filling ring 19a is between section 8 andclosure web 21 having gear teeth 19 at the periphery of the ring, whichring has a cylindrical section 19b inserted within the flange 17 of thesecond drum. Teeth 19 mesh with the teeth 10 as shown.

The heavier section 17 of the flange of said drum, at its outer side isprovided with a helical or spiral groove 23 of progressively increasingdiameter from one end to the other. Within the cylindrical section 19b,a spring 24, similar to the spring 14, and which is of spring ribbonstock and similar to clock main springs, has its outer end attached tothe part 19b and the inner end secured to the hub 20.

A tape or cable 26 is secured at one end to the reduced diameter portion18 of the last described drum which, at its outer end, leads therefromdownwardly through the bottom 1 of the housing as shown in Fig. 5. Suchtape or cable wound around the drum in several layers or windings may bepulled out when a window sash to which connected is lowered and woundaround the portion 18 when the sash is lifted.

The springs are given an initial force manually through the mechanismwhich is shown in Figs. 4 and 5. A gear 27 is in mesh with the teeth 13.It is at one end of a shaft, mounted horizontally for rotation on asupporting bracket 28, and may be manually actuated from below thebottom of the housing by turning a vertically positioned worm '29rotatably mounted on the same bracket, the lower end of the worm 29having a slot to receive a screwdriver. The bracket 28 is permanentlysecured at the upper side of the bottom 1 of the housing.

On turning the worm 29 to wind the springs, the web 12 is turned aboutthe axis of shaft 5 and through the intermeshing engagement of the teeth13 with teeth 22 web 21 is turned, thereby winding the spring 24 whichwill turn the member 19a, and through the teeth 19 thereon in mesh withthe teeth 10, actuate the first described drum to wind the spring 14.Thus both springs are wound to an initial tension with the drumconsisting of the parts 16 and 18 at rest and not moved by such initialspring winding. Of course at any time after the balance is installed, itmay be further wound or unwound as conditions may require. The worm 29and gear 27, which is of a worm tangent type, provide inherently a lockor stop against the springs unwinding after they have been wound to adesired point of tension.

A cable is connected at one end to the smaller diameter flange portion 8of the first drum, is.wound around the surface 9 thereof in severalturns and leads to the spiral groove 23 cut in the flange portion 17 ofthe second described drum. It is connected at its opposite end to suchdrum. When the tape or cable 26 is pulled outwardly on downward movementof a window sash to which the cable is attached, such second drum isturned in one direction and the first described drum is turned in theopposite direction, the cable unwinding from the first drum to thesecond drum and following the helical groove 23 as it is wound on to thesecond drum. In such down ward movement the forces of the springs 14 and24 are increased. The cable 25 unwinds from the second described drum tothe first, and when fully unwound is at the portion of the groove 23which has the smallest radius.

The reverse occurs on lifting the sash, the springs unwinding and theirforces aiding to lift the sash. The cable 25 is wound on to the firstdescribed drum from the second described drum, and because of thehelical groove 23, the radial distance of the tangential points ofcontact of cable 25 from the center of the axis 4 of such described drumprogressively increasing, reaching its maximum when the window sash isin upper position and the spring force correspondingly progressivelydecreased.

Two of the balances may be used in connection with a vertically slidablewindow sash mounted, one above and one toward each end of the upperhorizontal window frame 30 (Fig. 2), the frame having spaced verticalside frame members 31 and the sash 32 slidable vertically between them.With two of the sash balances as described, the two tapes or cables 26lead downwardly to the window sash, one at each side, and are connectedthereto.

As shown in Fig. 1, one only of the sash balances may be mountedadjacent one end and above the upper horizontal cross member 30 of thewindow frame, the tape or cable 26 extending downwardly and connected atthe adjacent side of the window 32. A second cable or tape 26a is woundwithin the tape or cable 26, and leads from the second described drum,which turns about the axis of the arbor 4, over the first drum outwardlyand to and over an idle roller 32a near the opposite end of the framemember 30, and thence downwardly to the opposite side of the window sash32. I

In either case when the sash is moved downwardly, the springs 14 and 24are wound to increase their force, and the cable 25 is unwound from thehelical groove 23 so that when the sash is at its lowermost position,the end of the cable 25 is nearest to the axis of the shaft 4, theretaking place a progressive decrease in length of the moment arm throughwhich the springs act. Their force is transmitted through the cable 25initially to the second described drum rotatably mounted to turn aboutthe shaft 4, and through the gearing connections described, theprogressively increasing power of the springs 14 and 24 is substantiallymatched or balanced by a progressive decrease in the effective moment orlever arm through which the force is transmitted eventually to the tapeor cable 26 attached to the window sash.

When the sash is lifted the reverse occurs, and while the force or powerof the springs is progressively decreased, the lever arm or moment armthrough which the forces act is progressively increased.

In Figs. 7' to 9 inclusive, a balance for a light weight window sash isshown. It includes a housing having a horizontal bottom 33, a verticalside 34 with which integral ends and top 35 may be formed, and a secondspaced vertical side 36. A shaft or arbor 37 is mounted at its ends andextends between the vertical sides 34 and 36 (Fig. 8). A drum has agenerally vertical web 38 rotatably mounted adjacent one end of theshaft 37 and against the vertical side 34, such web inclining upwardlyand outwardly to provide a conical form, in

whicha continuous helical groove 39, similar to the previouslydescribed, cable receiving groove 23 is. cut or otherwise formed. Thedrum is completed by a cylindrical flange 40 reaching substantially tothe opposite vertical side 36. A- sleeve 41 extends over the shaft 37and, at its outerv end, has aninterlocking connection with the side 36.to hold such sleeve against rotation. A wound. band spring 42. has itsinner end connected with the sleeve 41 and its outer end with the flange40. A cable 43 issecured to theweb 38 of the drum, at the end of thegroove'39 nearest the axis of the shaft 37 about which thedrum turns.Such cable 43 leads downwardly and outwardly to a change direction idleroller 44, which is rotatably andslidably mounted on a cross shaft 45between the sides of the housing (Fig. 9). Such cable extends downwardlythrough an opening in the bottom 33 of the housing and, in use, isconnected at one side and near the upper end of a vertically slidableshaft in a window frame, two of the balances being used in connectiontherewith, asin Fig. 2, for each of the window sashes in a window.frame.

In Fig. 7, the relative location of the cable 43 with respect to thegroove39 in-which it lies is shown when a window sash is at itslowermost position. In such position the spring42 is wound to-have itsmaximum force or power, but the distance from the cable to the center ofthe-shaft 37 is at aminimum, therefore, the effective moment arm, whichis such distance, is at a minimum, when the spring force is at itsmaximum. As the sash is lifted, the spring acts through the cable 43 tosubstantially balance the weight of the sash. With the decreasing forceof the spring as it unwinds, the distance from where the cable acts onthe drum progressively increases. Therefore, when the sash is lifted toits uppermost position, and the force of the spring is at its minimum,the moment or lever arm through which such force acts is at its maximum.

In Figs. to 12 inclusive, a third embodiment of the invention is shownwhich may be used for window sashes of intermediate weights between thelight weight window sashes and the heavy window sashes. In thisstructure a housing similar to the housing shown in Fig. 1 is used,having spaced vertical sides 46 and 47, closed by the ends and top 48,all preferably of sheet metal. A shaft or arbor 50 is between theopposite sides of the housing, toward one end thereof, on which a drumis mounted having a hub 51, a web of generally conical form at the outerside of which a continuous helical groove 52, like the previouslydescribed grooves 23 and 39, is made, the drum being completed by anannular flange 53, around which the tape or cable 54 to extend therefromthrough the bottom of the housing and connect with a window sash iswound. A second shaft or arbor 55, parallel to and in the same planewith the shaft 50, is mounted on and between the sides of the housingtoward the other end thereof. Two drums are mounted to turn about suchshaft. One of said drums has 'a hollow hub 59, a web 57 and a flange 58(Fig. 12). The other has a hollow hub 59, a web 61 and a flange 61. Thetwo hubs 56 and 59 telescope over the shaft 55 from opposite endsthereof, and the hubs coming together are provided, one with tongues,and one with slots (Fig. 12) so that they, are interlocked and rotatetogether.

A sleeve 62 covers both of said hubs and extends between the two webs 57and 60. Said sleeve, substantially midway between its ends, has acontinuous annular projection integral therewith extending outwardlywhich, preferably, is of 'a square outline, though it may be of anyequivalent out-of-round shape. A gear 64 having a central opening tocorrespond with the shape of the projection 63 is located thereoverbetween the two drums. A helically wound band spring 65, similar to theother clock type springs in previously described embodiments of theinvention, have their inner ends secured to the sleeve 62. The outerends of said springs are secured to the. flanges of. the respective.drums within which they are housed.

The springs may be initially wound to a desired tension, or may 'bewound or unwound after initial winding, by a worm shaft 66 which mesheswith the gear 64, mounted for rotation on a bracket 67 between thedrums, the bracket being secured to the bottom of the housing, as inFig. 11. One end of the shaft 67 is slotted for screwdriver connectiontherewith to turn it, the slotted end of the shaft being accessiblethrough an opening in the housing bottom.

A cable 68 wound around the flange 58 of one of said drums extends toand is connected to the web of, the drum having the helical groove 52therein. In thisstructure, as in the others, with the tapes or cables 54secured one at each side of a vertically slidable sash, as in Fig. 2,when the sash is lowered the springs are simultaneously wound to greaterstrength, and the point of tangential engagement of the tape or cable 54with its drum moves progressively inward toward the central axis of theshaft 50 about which the drum turns. Conversely, when a shaft is lifted,the force of the springs is exerted through the cable tohelp in liftingthe sash and substantially overcome the weight thereof. The springs inthe drums progressively unwindand the radial distances of thecontinuously changing points of tangential engagement of the tape orcable 54 with the drum progressively increases, the same effect beingproduced as in the previously described structures.

It is to be understood that while the disclosure of the invention in itsuse has been in connection with sliding window sashes, and that such usewith sliding window sashes is one of the primary places of use of theinvention, it is not restricted thereto alone, but may be used in manyother instances, as in balancing garage doors or other closures.

With the present invention, because of the generally constant value ofthe changing spring power multiplied by its changing lever or momentarm, the constant weight of a window sash is taken care of in aparticularly simple, practical and useful manner. With progressiveincrease in spring strength and power there is a substantiallyprogressive compensating decrease in the moment or lever arm throughwhich the spring strength or power acts and vice versa. Therefore, asash maybe raised and lowered far greater distances than in previousbalances, wherein, in use, the weight of the sash is constant, but theprogressively changing spring force or power, multiplied by a constantlever or moment arm, results in limiting the distance to which a sashcan be successfully and practically raised and lowered. This wasparticularly the case with the heavy window sashes of large size andwhich, in practice, have the longest vertical distances of movement inopening and closing.

The invention is defined in the appended claims, and is to be consideredcomprehensive of all forms of structure coming within their scope.

I claim:

1. A balance for a window sash comprising, a housing having spacedvertical sides, two horizontally spaced shafts supported by andextending between the housing sides, a drum having a horizontal hubrotatively mounted on one of said shafts, a web of circular formconnected with and extending vertically from the hub, and a cylindricalflange at the outer edges of the web, said web at its outer side havinga helical groove with one end located inwardly from said flange and theother end adjacent the flange, said groove progressively increasing inradius from the first mentioned to the last mentioned ends of thegroove, a tape wound on said flange, a second drum mounted on the secondshaft having a hub, web and flange, a cable connected at one end withthe first drum adjacent the outer end of said groove and to the seconddrum flange, windable on said last mentioned flange, and

ond drum, normally tending to rotate said second drum in a direction towind the said cable onto the flange there- 'of, said spring meansprogressively decreasing in force, and resistingly yieldable to windsaid cable into said groove of the first drum and unwind the tapetherefrom, said spring means having increasing resisting force as thecable is wound into said groove due to the helical shape of the groove.

2. A balance for a window sash comprising a base, side walls attached toa longitudinal edge of the base, a pair of shafts having their endsfixed in said side walls, drums mounted on said shafts, sleeves on saidshafts, springs 'fixed at one end to the interior of the drums and atthe other ends to the said sleeves in a manner whereby rotation of thedrums will tension the springs, one of said' drums having a surfacehaving a helical groove of progressively changing diameter therein theother drum having a cylindrical portion, a cable attached at one end toone of the drums at the helical groove therein and at its other end tothe said cylindrical portion of the other drum, whereby rotation of thefirst drum will cause rotation of the other drum, a sash cord attachedto a cylindrical portion of the first drum and adapted to be wound onsaid cylindrical portion, the groove by virtue of the changing diameterthereof providing a power differential in the drive from one drum to theother.

3. A balance for a window sash comprising a base, a pair of spacedvertical side walls extending upwardly from opposite longitudinal edgesof the base, two spaced horizontal shafts secured at their ends in saidside walls, a drum having a horizontal hub rotatively mounted on one ofsaid shafts, a circular web connected to said hub, a cylindrical flangeat the outer edge of the web, said web having a helical groove at oneside with a progressively changing radius, a second drum mounted on theother shaft, said drum having a hub web and flange, a cable connected atone end to the first drum adjacent the outer end of the helical grooveand to the second drum flange and windable in said helical groove, coilsprings within said drums and connected at one end to the interior ofthe drums and at the other end to the said hubs, manually operated meansfor simultaneously tensioning said springs, and a sash cable attached toand adapted to be wound on said first named drum.

References Cited in the file of this patent UNITED STATES PATENTS479,150 Kimball July 19, 1892 820,962 Erb May 22, 1906 1,599,872 BraenSept. 14, 1926 1,898,584 Mantz Feb. 21, 1933 2,679,659 Grupp June 1,1954

